Preparation of Benzocaine

When p-nitrotoluene is used as a raw material to synthesize ethyl p-aminobenzoate (ie, benzocaine), in the esterification reaction, concentrated sulfuric acid is generally used as a catalyst, and the yield of benzocaine is relatively low. The Lewis acid was used as a catalyst to find that the yield of benzocaine can be increased to 67%.

The multi-step reaction of p-methylaniline as raw material for the synthesis of benzocaine was studied. The experimental phenomena abnormalities occurred during the experiment were solved, the product purification was difficult, the yield was low, and there was no product. The improved experimental conditions were completed. Experiment, the product yield is high, and the experiment reproducibility is good.

Based on the better synthetic route, the experimental study was carried out to synthesize ethyl p-nitrobenzoate by microwave irradiation with p-toluenesulfonic acid in the esterification reaction stage. Results: the esterification reaction time was shortened to 11 min, and the esterification reaction yield was 96.5. %; After the process is improved, the total yield of esterification and reduction is 81.1%, which is greatly improved.

Synthesis of other derivatives

The benzocaine was linked to methacrylic acid via an ester bond to synthesize a benzocaine-containing polymerizable monomer (BM). The BM was self-polymerized to obtain a benzocaine polymer carrier drug (PBM), and emulsion polymerization was carried out. The structure of PBM nanospheres was prepared by 1H NMR and TEM.

Synthesis of benzocaine by oxidation, esterification and reduction with p-nitrotoluene as raw material, and then reacting benzocaine with p-fluorobenzaldehyde to form a novel benzocaine derivative (4-formyl-4) The structure of '-ethoxycarbonyldiphenylamine) was confirmed by IR, 1 H NMR and elemental analysis. The synthesis conditions were studied. The effects of reaction temperature and reaction time on the reaction system were discussed.

1. It is obtained by reduction of ethyl p-nitrobenzoate by iron powder.
2. The esterification method is mainly used. First, the p-aminobenzoic acid is hydrogenated to form p-aminobenzoic acid, and then esterified with ethanol in the presence of a sulfuric acid catalyst, followed by neutralization, washing, crystallization, and drying.